Eastern Pacific Hurricane Season

Although some residents of the eastern United States may not pay as much attention to it as the Atlantic Season, the Eastern Pacific hurricane season also concludes on November 30.  The eastern Pacific is typically a little busier than the tropical Atlantic.  Both seasons were busier than average in 2017.  

NOAA data shows the eastern Pacific (west of Central America) sees 15 tropical storms, 8 hurricanes, including 4 “major” hurricanes in an average season.  This year featured 18 tropical storms and 9 hurricanes, of which 4 were major.  A “major” hurricane is defined as a Category 3 or greater storm on the Saffir-Simpson scale with sustained winds of 111 mph or greater.  Hurricane season in the eastern Pacific runs from May 15 through November 30, while the Atlantic season starts June 1. 

The eastern Pacific’s first tropical storm of 2017 occurred on May 10 when “Adrian” developed.  An otherwise unremarkable storm, Tropical Storm Adrian set a record for earliest named storm in the Eastern Pacific.  NOAA records show the previous record holder was 1990’s Hurricane Alma (that developed on May 12).  Tropical Storm Selma was the last named storm to develop in the eastern Pacific and dissipated on October 28, 2017. 

The eastern Pacific’s (sometimes abbreviated as “EPAC”) strongest storm of 2017 was Category 4 Hurricane Fernanda in mid-July.  At peak intensity, Fernanda had sustained winds of 145 mph and a minimum central pressure of 947 millibars (mb).  Despite being an active season, Fernanda was the EPAC’s weakest-strongest storm of the season since 2013.

Unlike the 2014-2015 seasons when several devastating EPAC hurricanes developed and made landfall (including Odile and Patricia), the only hurricane to make landfall in 2017 was Max.  “Max” was a minimal Category 1 storm that made landfall on September 14 on the west coast of Mexico.  

By comparison, the Atlantic Ocean Basin produced several destructive hurricanes in 2017.  Of the 17 tropical storms and 10 hurricanes, including 6 major hurricanes, the United States had three Category 4 hurricanes make landfall (Harvey, Irma, Maria).

Notable November Hurricanes

Hurricane Otto in 2016  (Source: NOAA)

The Atlantic hurricane season runs from June through November.  September is the busiest month of the season, after which tropical activity tends to fall precipitously as conditions become less favorable.  That said, there have been several significant November hurricanes worthy of discussion. 

Otto (2016):  Otto attained hurricane status in the Caribbean Sea on November 23 and intensified into a major, Category 3 hurricane with sustained winds of 115 mph.  Otto made landfall in Nicaragua on November 24 at peak intensity and was the latest landfalling Atlantic hurricane in modern history.  The National Hurricane Center tracked Otto as it crossed Central America into the eastern Pacific Ocean.  Otto was the first tropical system since 1996 to cross Central America and emerge in the Pacific Ocean.  Otto was the 15^th and final named storm of the 2016 season. 

Michelle (2001):  Not only was Michelle the strongest hurricane of the 2001 season, it was also one of the strongest November hurricanes on record in the Atlantic Ocean Basin.  Michelle, on November 3 reached Category 4 intensity with sustained winds of 140 mph.  It became the strongest hurricane to make landfall in Cuba since 1952.  Its minimum air pressure of 933 millibars (mb) was lower than last year’s Category 5 Hurricane Matthew’s lowest pressure of 934 mb.

Lenny (1999):  On November 17, 1999, Lenny made landfall on the island of St. Croix with sustained winds of 155 mph, nearly Category 5 intensity.  Although Lenny’s minimum central air pressure of 933 mb was the same as Michelle’s two years later, Lenny’s peak winds were higher.  Lenny was not only noteworthy for being the strongest November hurricane of the satellite era, but was also significant for its track.  Hurricanes normally track from east to west in the Northern Hemisphere.  However, being a late season storm, Lenny, tracked west to east across the Caribbean Sea.

Kate (1985):  Kate reached peak intensity in the Gulf of Mexico on November 20 with sustained winds of 120 mph and a minimum central air pressure of 953 mb.  Kate weakened slightly to a Category 2 storm before making landfall on the Florida Peninsula on November 21.  It was the fourth hurricane to impact the U.S. Gulf Coast during the 1985 season.  Hurricane Kate was also the latest landfalling hurricane on record in the contiguous United States.

A Taste of Winter

There has been a dramatic swing in temperatures in the DC Metro Area over the first two weeks of November.  This month got off to an exceptionally warm start over the first six days, with November 3 being the warmest day of the month.  Its high and low temperatures of 78° and 58° are more typical of late May.

Following the very warm start to the month, there was a major shift in the weather pattern and the last eight days have been significantly cooler than average in the DC Metro.  This past Saturday, November 11, has been the coldest day so far this month with a high/low temperature of 39°/26°. 

That was DC’s coldest November day since November 25, 2013 (38°/24°) and coldest day overall since March 15, 2017 (33°/22°).  To add to that, the November 11 low temperature of 26° tied the record low for the date and was DC’s first record low temperature in November since 1976.  Consequently, the average monthly temperature through November 13 in the Nation’s Capital is 1.1° below average. 

This month had measurable rainfall on six of the first 14 days for a total of 1.91” of rain, making it 0.55” wetter than average so far.  The wettest day was November 7, when 1.07” fell at National Airport.  That was DC’s largest daily rainfall total since August 7 (1.47”).  The last time 1.00”/+ fell on a November day in DC was on November 26, 2014 (1.06”).

Although every November since 2009 has been drier than average, only the last three have been warmer than average.  That underscores how much weather variability Washingtonians can experience in November.  NOAA expects the below average temperatures to continue over much of the eastern United States for the next two weeks.  If November 2017 finishes as a cooler than average month in the Nation’s Capital, then it would be only the third cooler than average month of 2017.  However, November’s weather is not a good indicator of what the upcoming winter weather will be like.